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Old 27th April 2009, 17:04   #1
eamon38
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Default No initial power?

Hello Rover Buddies.
I have a 2002- 75 2.5 V6 auto -68k When I start the car (which is not a problem) especially in the morning I have no power when I put it in gear?In neutral the car will rev,no problem,but when I put it into gear it will not go?It takes it a few minutes to actually wake up!Then it is fine for the rest of the day!I can only let it twiddle along at idle speed and keep coaxing it until it feels like taking the juice.
Engine management goes off n on on any given day and is not consistent.
I have changed the 3 lamda sensors on many occasions which seem to help every now and again.
What am I missing.
Is 19.6 MPG what everybody else is getting or have I got a Petro-holic?
The oil has been changed in the transmission.I have an in line filter on the fuel and in general the car is well serviced.

Last edited by eamon38; 27th April 2009 at 17:08.. Reason: more stuff
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Old 27th April 2009, 17:14   #2
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welcome along...

Depending on your journey, 19mpg is possible if are making lots of urban journeys.

Not sure why you've got an additional filter added

If you've changed 3 sensors, it would suggest there is a problem. You really need to get the car to an Xpart dealer with a t4 machine.
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Old 27th April 2009, 18:29   #3
eamon38
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Quote:
Originally Posted by Greeners View Post
welcome along...

Depending on your journey, 19mpg is possible if are making lots of urban journeys.

Not sure why you've got an additional filter added

If you've changed 3 sensors, it would suggest there is a problem. You really need to get the car to an Xpart dealer with a t4 machine.
Thanks for the reply...I do a round trip of 12 miles a day to work at approx 45 mph all the way and cant get any more than 19.6.On a long trip every weekend I can manage 24 ish? Reading tonights forum maybe its a VIS problem.I have also changed these which i have found to be the same on the 20 ltr V6.How hard are these to repair?is it the motor that gives up or is it the mechanical part.?
I have also found that any Lamda sensor will work if it has the same amount of wires.I have "operated" on many different types and studied the workings.Almost all have the same thread and are only made by a few companies.So just cut and join...it has worked for me.I have previously worked and live close to a VERY large Auto breakers,if you need a part or two.
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Old 27th April 2009, 18:37   #4
Fraser Mitchell
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The car should detect when a load is put on the engine in the absence of throttle opening. Does it die when the air-con is turned on ? Better chaps than me can tell you how the EMS detects engine load.
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Old 27th April 2009, 21:16   #5
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The car should detect when a load is put on the engine in the absence of throttle opening. Does it die when the air-con is turned on ? Better chaps than me can tell you how the EMS detects engine load.
Tried the A/C ...no doesn't die?
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Old 28th April 2009, 19:11   #6
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It sounds like a dodgy sensor somewhere, but which one !!

If its not OK at cold but OK when hot there might be a problem with the engine coolant temperature sensor. Think of it this way, the mass airflow plus the engine temperature gives an arithmetic value which is then compared to a fuelling map in the ECU. If the coolant sensor reports the engine is warmer than it is then insufficient fuel is going to be commanded by the ECU for what is a cold engine. The other ECU adjustments via other sensors are mostly just trimming adjustments, although there is an input on speed of throttle opening which has a fairly large effect once the car is moving.

If the MAF sensor was dodgy the effect should be at all engine temperatures

At least that is how I see it !
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Old 30th April 2009, 16:40   #7
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When cold, the engine is working in open loop and this has nothing to do with lambda sensors.
Afaik, KV6 doesn't have a MAF.
ECU can be fooled if the temperature sensor is not working properly and the ECU decides that it's hot, unlikely but possible.
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